Different attempts of integrating virtual representations of physical objects into a virtual game play have been made. However, a close link between the physical world and a virtual game play stimulating the interactive involvement of the user and, in particular, stimulating the development of different skills by children's game playing is still missing. Therefore there is a need for a new approach to interactive game play.
Most toy-enhanced computer games or so-called toys-to-life systems currently involve systems wherein toys must have a physical component configured to communicate with a special reader via some form of wireless communication like RFID, NFC etc. Examples of such systems are disclosed in e.g. US 2012/0295703, EP 2749327 and US 2014/256430. It would be generally desirable to provide game systems that do not require the toy to comprise elements that are capable of communicating with a reader device so as to be able to identify a toy element, and to create its virtual digital representation and associate it with additional digital data.
WO 2011/017393 describes a system that uses computer vision to detect a toy construction model on a special background. To this end, an assembled model is on a special background plate with a specific pattern printed on it. In some systems the image-acquiring device may even need to be aligned to a specific angle relative to the toy element assembly for the recognition to take place. It would thus generally be desirable to increase the robustness of such methods, e.g. by reducing their sensitivity to one or more of the following parameters: The distance between a toy element from the image acquiring device, for example a camera, the rotation of the toy element, the angle of the camera, the background, the illumination, or the need for a predefined region where a toy element should be placed.
Document U.S. Pat. No. 8,855,366 discloses a method and apparatus for tracking three-dimensional (3D) objects. This prior art method of tracking a 3D object includes constructing a database to store a set of two-dimensional (2D) images of the 3D object using a tracking background, where the tracking background includes at least one known pattern, receiving a tracking image, determining whether the tracking image matches at least one image in the database in accordance with feature points of the tracking image, and providing information about the tracking image in respond to the tracking image matches the at least one image in the database. The method of constructing a database also includes capturing the set of 2D images of the 3D object with the tracking background, extracting a set of feature points from each 2D image, and storing the set of feature points in the database. However, the above prior art method requires the extraction of feature points and it requires a tracking background. It would thus be desirable to provide a method that is robust with respect to the choice of background and with respect to the rotation of the object. Accordingly it is desirable to provide a robust method that enables easy application. It is further desirable to provide a method that results in accurate detection and recognition. In particular, it is desirable to provide a method whose accuracy of recognition depends only little on factors such as rotation, size, scale, illumination or background change.